aboutsummaryrefslogtreecommitdiff
path: root/tools/lib/bpf/linker.c
diff options
context:
space:
mode:
Diffstat (limited to 'tools/lib/bpf/linker.c')
-rw-r--r--tools/lib/bpf/linker.c105
1 files changed, 80 insertions, 25 deletions
diff --git a/tools/lib/bpf/linker.c b/tools/lib/bpf/linker.c
index e0005c6ade88..cf71d149fe26 100644
--- a/tools/lib/bpf/linker.c
+++ b/tools/lib/bpf/linker.c
@@ -20,6 +20,7 @@
#include "btf.h"
#include "libbpf_internal.h"
#include "strset.h"
+#include "str_error.h"
#define BTF_EXTERN_SEC ".extern"
@@ -135,6 +136,7 @@ struct bpf_linker {
int fd;
Elf *elf;
Elf64_Ehdr *elf_hdr;
+ bool swapped_endian;
/* Output sections metadata */
struct dst_sec *secs;
@@ -305,7 +307,7 @@ static int init_output_elf(struct bpf_linker *linker, const char *file)
linker->fd = open(file, O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC, 0644);
if (linker->fd < 0) {
err = -errno;
- pr_warn("failed to create '%s': %d\n", file, err);
+ pr_warn("failed to create '%s': %s\n", file, errstr(err));
return err;
}
@@ -324,13 +326,8 @@ static int init_output_elf(struct bpf_linker *linker, const char *file)
linker->elf_hdr->e_machine = EM_BPF;
linker->elf_hdr->e_type = ET_REL;
-#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
- linker->elf_hdr->e_ident[EI_DATA] = ELFDATA2LSB;
-#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
- linker->elf_hdr->e_ident[EI_DATA] = ELFDATA2MSB;
-#else
-#error "Unknown __BYTE_ORDER__"
-#endif
+ /* Set unknown ELF endianness, assign later from input files */
+ linker->elf_hdr->e_ident[EI_DATA] = ELFDATANONE;
/* STRTAB */
/* initialize strset with an empty string to conform to ELF */
@@ -396,6 +393,8 @@ static int init_output_elf(struct bpf_linker *linker, const char *file)
pr_warn_elf("failed to create SYMTAB data");
return -EINVAL;
}
+ /* Ensure libelf translates byte-order of symbol records */
+ sec->data->d_type = ELF_T_SYM;
str_off = strset__add_str(linker->strtab_strs, sec->sec_name);
if (str_off < 0)
@@ -539,19 +538,21 @@ static int linker_load_obj_file(struct bpf_linker *linker, const char *filename,
const struct bpf_linker_file_opts *opts,
struct src_obj *obj)
{
-#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
- const int host_endianness = ELFDATA2LSB;
-#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
- const int host_endianness = ELFDATA2MSB;
-#else
-#error "Unknown __BYTE_ORDER__"
-#endif
int err = 0;
Elf_Scn *scn;
Elf_Data *data;
Elf64_Ehdr *ehdr;
Elf64_Shdr *shdr;
struct src_sec *sec;
+ unsigned char obj_byteorder;
+ unsigned char link_byteorder = linker->elf_hdr->e_ident[EI_DATA];
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+ const unsigned char host_byteorder = ELFDATA2LSB;
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+ const unsigned char host_byteorder = ELFDATA2MSB;
+#else
+#error "Unknown __BYTE_ORDER__"
+#endif
pr_debug("linker: adding object file '%s'...\n", filename);
@@ -560,7 +561,7 @@ static int linker_load_obj_file(struct bpf_linker *linker, const char *filename,
obj->fd = open(filename, O_RDONLY | O_CLOEXEC);
if (obj->fd < 0) {
err = -errno;
- pr_warn("failed to open file '%s': %d\n", filename, err);
+ pr_warn("failed to open file '%s': %s\n", filename, errstr(err));
return err;
}
obj->elf = elf_begin(obj->fd, ELF_C_READ_MMAP, NULL);
@@ -577,11 +578,25 @@ static int linker_load_obj_file(struct bpf_linker *linker, const char *filename,
pr_warn_elf("failed to get ELF header for %s", filename);
return err;
}
- if (ehdr->e_ident[EI_DATA] != host_endianness) {
+
+ /* Linker output endianness set by first input object */
+ obj_byteorder = ehdr->e_ident[EI_DATA];
+ if (obj_byteorder != ELFDATA2LSB && obj_byteorder != ELFDATA2MSB) {
err = -EOPNOTSUPP;
- pr_warn_elf("unsupported byte order of ELF file %s", filename);
+ pr_warn("unknown byte order of ELF file %s\n", filename);
return err;
}
+ if (link_byteorder == ELFDATANONE) {
+ linker->elf_hdr->e_ident[EI_DATA] = obj_byteorder;
+ linker->swapped_endian = obj_byteorder != host_byteorder;
+ pr_debug("linker: set %s-endian output byte order\n",
+ obj_byteorder == ELFDATA2MSB ? "big" : "little");
+ } else if (link_byteorder != obj_byteorder) {
+ err = -EOPNOTSUPP;
+ pr_warn("byte order mismatch with ELF file %s\n", filename);
+ return err;
+ }
+
if (ehdr->e_type != ET_REL
|| ehdr->e_machine != EM_BPF
|| ehdr->e_ident[EI_CLASS] != ELFCLASS64) {
@@ -656,7 +671,8 @@ static int linker_load_obj_file(struct bpf_linker *linker, const char *filename,
obj->btf = btf__new(data->d_buf, shdr->sh_size);
err = libbpf_get_error(obj->btf);
if (err) {
- pr_warn("failed to parse .BTF from %s: %d\n", filename, err);
+ pr_warn("failed to parse .BTF from %s: %s\n",
+ filename, errstr(err));
return err;
}
sec->skipped = true;
@@ -666,7 +682,8 @@ static int linker_load_obj_file(struct bpf_linker *linker, const char *filename,
obj->btf_ext = btf_ext__new(data->d_buf, shdr->sh_size);
err = libbpf_get_error(obj->btf_ext);
if (err) {
- pr_warn("failed to parse .BTF.ext from '%s': %d\n", filename, err);
+ pr_warn("failed to parse .BTF.ext from '%s': %s\n",
+ filename, errstr(err));
return err;
}
sec->skipped = true;
@@ -1109,6 +1126,24 @@ static bool sec_content_is_same(struct dst_sec *dst_sec, struct src_sec *src_sec
return true;
}
+static bool is_exec_sec(struct dst_sec *sec)
+{
+ if (!sec || sec->ephemeral)
+ return false;
+ return (sec->shdr->sh_type == SHT_PROGBITS) &&
+ (sec->shdr->sh_flags & SHF_EXECINSTR);
+}
+
+static void exec_sec_bswap(void *raw_data, int size)
+{
+ const int insn_cnt = size / sizeof(struct bpf_insn);
+ struct bpf_insn *insn = raw_data;
+ int i;
+
+ for (i = 0; i < insn_cnt; i++, insn++)
+ bpf_insn_bswap(insn);
+}
+
static int extend_sec(struct bpf_linker *linker, struct dst_sec *dst, struct src_sec *src)
{
void *tmp;
@@ -1168,6 +1203,10 @@ static int extend_sec(struct bpf_linker *linker, struct dst_sec *dst, struct src
memset(dst->raw_data + dst->sec_sz, 0, dst_align_sz - dst->sec_sz);
/* now copy src data at a properly aligned offset */
memcpy(dst->raw_data + dst_align_sz, src->data->d_buf, src->shdr->sh_size);
+
+ /* convert added bpf insns to native byte-order */
+ if (linker->swapped_endian && is_exec_sec(dst))
+ exec_sec_bswap(dst->raw_data + dst_align_sz, src->shdr->sh_size);
}
dst->sec_sz = dst_final_sz;
@@ -2415,6 +2454,10 @@ static int linker_append_btf(struct bpf_linker *linker, struct src_obj *obj)
if (glob_sym && glob_sym->var_idx >= 0) {
__s64 sz;
+ /* FUNCs don't have size, nothing to update */
+ if (btf_is_func(t))
+ continue;
+
dst_var = &dst_sec->sec_vars[glob_sym->var_idx];
/* Because underlying BTF type might have
* changed, so might its size have changed, so
@@ -2628,6 +2671,10 @@ int bpf_linker__finalize(struct bpf_linker *linker)
if (!sec->scn)
continue;
+ /* restore sections with bpf insns to target byte-order */
+ if (linker->swapped_endian && is_exec_sec(sec))
+ exec_sec_bswap(sec->raw_data, sec->sec_sz);
+
sec->data->d_buf = sec->raw_data;
}
@@ -2696,6 +2743,7 @@ static int emit_elf_data_sec(struct bpf_linker *linker, const char *sec_name,
static int finalize_btf(struct bpf_linker *linker)
{
+ enum btf_endianness link_endianness;
LIBBPF_OPTS(btf_dedup_opts, opts);
struct btf *btf = linker->btf;
const void *raw_data;
@@ -2729,17 +2777,24 @@ static int finalize_btf(struct bpf_linker *linker)
err = finalize_btf_ext(linker);
if (err) {
- pr_warn(".BTF.ext generation failed: %d\n", err);
+ pr_warn(".BTF.ext generation failed: %s\n", errstr(err));
return err;
}
opts.btf_ext = linker->btf_ext;
err = btf__dedup(linker->btf, &opts);
if (err) {
- pr_warn("BTF dedup failed: %d\n", err);
+ pr_warn("BTF dedup failed: %s\n", errstr(err));
return err;
}
+ /* Set .BTF and .BTF.ext output byte order */
+ link_endianness = linker->elf_hdr->e_ident[EI_DATA] == ELFDATA2MSB ?
+ BTF_BIG_ENDIAN : BTF_LITTLE_ENDIAN;
+ btf__set_endianness(linker->btf, link_endianness);
+ if (linker->btf_ext)
+ btf_ext__set_endianness(linker->btf_ext, link_endianness);
+
/* Emit .BTF section */
raw_data = btf__raw_data(linker->btf, &raw_sz);
if (!raw_data)
@@ -2747,7 +2802,7 @@ static int finalize_btf(struct bpf_linker *linker)
err = emit_elf_data_sec(linker, BTF_ELF_SEC, 8, raw_data, raw_sz);
if (err) {
- pr_warn("failed to write out .BTF ELF section: %d\n", err);
+ pr_warn("failed to write out .BTF ELF section: %s\n", errstr(err));
return err;
}
@@ -2759,7 +2814,7 @@ static int finalize_btf(struct bpf_linker *linker)
err = emit_elf_data_sec(linker, BTF_EXT_ELF_SEC, 8, raw_data, raw_sz);
if (err) {
- pr_warn("failed to write out .BTF.ext ELF section: %d\n", err);
+ pr_warn("failed to write out .BTF.ext ELF section: %s\n", errstr(err));
return err;
}
}
@@ -2935,7 +2990,7 @@ static int finalize_btf_ext(struct bpf_linker *linker)
err = libbpf_get_error(linker->btf_ext);
if (err) {
linker->btf_ext = NULL;
- pr_warn("failed to parse final .BTF.ext data: %d\n", err);
+ pr_warn("failed to parse final .BTF.ext data: %s\n", errstr(err));
goto out;
}
generated by cgit (git 2.34.1) at 2025-05-29 21:50:50 +0000